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Java example source code file (ciStreams.cpp)

This example Java source code file (ciStreams.cpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

bytecodes\:\:_invokedynamic, bytecodes\:\:_ldc, bytecodes\:\:_ldc2_w, bytecodes\:\:_ldc_w, bytecodes\:\:_wide, bytecodes\:\:code, capture, constantpool, current_env-, guarded_vm_entry, shouldnotreachhere, skip, vm_entry_mark, word

The ciStreams.cpp Java example source code

/*
 * Copyright (c) 1999, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#include "precompiled.hpp"
#include "ci/ciCallSite.hpp"
#include "ci/ciConstant.hpp"
#include "ci/ciField.hpp"
#include "ci/ciStreams.hpp"
#include "ci/ciUtilities.hpp"

// ciExceptionHandlerStream
//
// Walk over some selected set of a methods exception handlers.

// ------------------------------------------------------------------
// ciExceptionHandlerStream::count
//
// How many exception handlers are there in this stream?
//
// Implementation note: Compiler2 needs this functionality, so I had
int ciExceptionHandlerStream::count() {
  int save_pos = _pos;
  int save_end = _end;

  int count = 0;

  _pos = -1;
  _end = _method->_handler_count;


  next();
  while (!is_done()) {
    count++;
    next();
  }

  _pos = save_pos;
  _end = save_end;

  return count;
}

int ciExceptionHandlerStream::count_remaining() {
  int save_pos = _pos;
  int save_end = _end;

  int count = 0;

  while (!is_done()) {
    count++;
    next();
  }

  _pos = save_pos;
  _end = save_end;

  return count;
}

// ciBytecodeStream
//
// The class is used to iterate over the bytecodes of a method.
// It hides the details of constant pool structure/access by
// providing accessors for constant pool items.

// ------------------------------------------------------------------
// ciBytecodeStream::next_wide_or_table
//
// Special handling for switch ops
Bytecodes::Code ciBytecodeStream::next_wide_or_table(Bytecodes::Code bc) {
  switch (bc) {                // Check for special bytecode handling
  case Bytecodes::_wide:
    // Special handling for the wide bytcode
    // Get following bytecode; do not return wide
    assert(Bytecodes::Code(_pc[0]) == Bytecodes::_wide, "");
    bc = Bytecodes::java_code(_raw_bc = (Bytecodes::Code)_pc[1]);
    assert(Bytecodes::wide_length_for(bc) > 2, "must make progress");
    _pc += Bytecodes::wide_length_for(bc);
    _was_wide = _pc;              // Flag last wide bytecode found
    assert(is_wide(), "accessor works right");
    break;

  case Bytecodes::_lookupswitch:
    _pc++;                      // Skip wide bytecode
    _pc += (_start-_pc)&3;      // Word align
    _table_base = (jint*)_pc;   // Capture for later usage
                                // table_base[0] is default far_dest
    // Table has 2 lead elements (default, length), then pairs of u4 values.
    // So load table length, and compute address at end of table
    _pc = (address)&_table_base[2+ 2*Bytes::get_Java_u4((address)&_table_base[1])];
    break;

  case Bytecodes::_tableswitch: {
    _pc++;                      // Skip wide bytecode
    _pc += (_start-_pc)&3;      // Word align
    _table_base = (jint*)_pc;   // Capture for later usage
                                // table_base[0] is default far_dest
    int lo = Bytes::get_Java_u4((address)&_table_base[1]);// Low bound
    int hi = Bytes::get_Java_u4((address)&_table_base[2]);// High bound
    int len = hi - lo + 1;      // Dense table size
    _pc = (address)&_table_base[3+len]; // Skip past table
    break;
  }

  default:
    fatal("unhandled bytecode");
  }
  return bc;
}

// ------------------------------------------------------------------
// ciBytecodeStream::reset_to_bci
void ciBytecodeStream::reset_to_bci( int bci ) {
  _bc_start=_was_wide=0;
  _pc = _start+bci;
}

// ------------------------------------------------------------------
// ciBytecodeStream::force_bci
void ciBytecodeStream::force_bci(int bci) {
  if (bci < 0) {
    reset_to_bci(0);
    _bc_start = _start + bci;
    _bc = EOBC();
  } else {
    reset_to_bci(bci);
    next();
  }
}


// ------------------------------------------------------------------
// Constant pool access
// ------------------------------------------------------------------

// ------------------------------------------------------------------
// ciBytecodeStream::get_klass_index
//
// If this bytecodes references a klass, return the index of the
// referenced klass.
int ciBytecodeStream::get_klass_index() const {
  switch(cur_bc()) {
  case Bytecodes::_ldc:
    return get_index_u1();
  case Bytecodes::_ldc_w:
  case Bytecodes::_ldc2_w:
  case Bytecodes::_checkcast:
  case Bytecodes::_instanceof:
  case Bytecodes::_anewarray:
  case Bytecodes::_multianewarray:
  case Bytecodes::_new:
  case Bytecodes::_newarray:
    return get_index_u2();
  default:
    ShouldNotReachHere();
    return 0;
  }
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_klass
//
// If this bytecode is a new, newarray, multianewarray, instanceof,
// or checkcast, get the referenced klass.
ciKlass* ciBytecodeStream::get_klass(bool& will_link) {
  VM_ENTRY_MARK;
  constantPoolHandle cpool(_method->get_Method()->constants());
  return CURRENT_ENV->get_klass_by_index(cpool, get_klass_index(), will_link, _holder);
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_constant_raw_index
//
// If this bytecode is one of the ldc variants, get the index of the
// referenced constant.
int ciBytecodeStream::get_constant_raw_index() const {
  // work-alike for Bytecode_loadconstant::raw_index()
  switch (cur_bc()) {
  case Bytecodes::_ldc:
    return get_index_u1();
  case Bytecodes::_ldc_w:
  case Bytecodes::_ldc2_w:
    return get_index_u2();
  default:
    ShouldNotReachHere();
    return 0;
  }
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_constant_pool_index
// Decode any reference index into a regular pool index.
int ciBytecodeStream::get_constant_pool_index() const {
  // work-alike for Bytecode_loadconstant::pool_index()
  int index = get_constant_raw_index();
  if (has_cache_index()) {
    VM_ENTRY_MARK;
    constantPoolHandle cpool(_method->get_Method()->constants());
    return cpool->object_to_cp_index(index);
  }
  return index;
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_constant_cache_index
// Return the CP cache index, or -1 if there isn't any.
int ciBytecodeStream::get_constant_cache_index() const {
  // work-alike for Bytecode_loadconstant::cache_index()
  return has_cache_index() ? get_constant_raw_index() : -1;
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_constant
//
// If this bytecode is one of the ldc variants, get the referenced
// constant.
ciConstant ciBytecodeStream::get_constant() {
  int pool_index = get_constant_raw_index();
  int cache_index = -1;
  if (has_cache_index()) {
    cache_index = pool_index;
    pool_index = -1;
  }
  VM_ENTRY_MARK;
  constantPoolHandle cpool(_method->get_Method()->constants());
  return CURRENT_ENV->get_constant_by_index(cpool, pool_index, cache_index, _holder);
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_constant_pool_tag
//
// If this bytecode is one of the ldc variants, get the referenced
// constant.
constantTag ciBytecodeStream::get_constant_pool_tag(int index) const {
  VM_ENTRY_MARK;
  return _method->get_Method()->constants()->tag_at(index);
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_field_index
//
// If this is a field access bytecode, get the constant pool
// index of the referenced field.
int ciBytecodeStream::get_field_index() {
  assert(cur_bc() == Bytecodes::_getfield ||
         cur_bc() == Bytecodes::_putfield ||
         cur_bc() == Bytecodes::_getstatic ||
         cur_bc() == Bytecodes::_putstatic, "wrong bc");
  return get_index_u2_cpcache();
}


// ------------------------------------------------------------------
// ciBytecodeStream::get_field
//
// If this bytecode is one of get_field, get_static, put_field,
// or put_static, get the referenced field.
ciField* ciBytecodeStream::get_field(bool& will_link) {
  ciField* f = CURRENT_ENV->get_field_by_index(_holder, get_field_index());
  will_link = f->will_link(_holder, _bc);
  return f;
}


// ------------------------------------------------------------------
// ciBytecodeStream::get_declared_field_holder
//
// Get the declared holder of the currently referenced field.
//
// Usage note: the holder() of a ciField class returns the canonical
// holder of the field, rather than the holder declared in the
// bytecodes.
//
// There is no "will_link" result passed back.  The user is responsible
// for checking linkability when retrieving the associated field.
ciInstanceKlass* ciBytecodeStream::get_declared_field_holder() {
  VM_ENTRY_MARK;
  constantPoolHandle cpool(_method->get_Method()->constants());
  int holder_index = get_field_holder_index();
  bool ignore;
  return CURRENT_ENV->get_klass_by_index(cpool, holder_index, ignore, _holder)
      ->as_instance_klass();
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_field_holder_index
//
// Get the constant pool index of the declared holder of the field
// referenced by the current bytecode.  Used for generating
// deoptimization information.
int ciBytecodeStream::get_field_holder_index() {
  GUARDED_VM_ENTRY(
    ConstantPool* cpool = _holder->get_instanceKlass()->constants();
    return cpool->klass_ref_index_at(get_field_index());
  )
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_field_signature_index
//
// Get the constant pool index of the signature of the field
// referenced by the current bytecode.  Used for generating
// deoptimization information.
int ciBytecodeStream::get_field_signature_index() {
  VM_ENTRY_MARK;
  ConstantPool* cpool = _holder->get_instanceKlass()->constants();
  int nt_index = cpool->name_and_type_ref_index_at(get_field_index());
  return cpool->signature_ref_index_at(nt_index);
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_method_index
//
// If this is a method invocation bytecode, get the constant pool
// index of the invoked method.
int ciBytecodeStream::get_method_index() {
#ifdef ASSERT
  switch (cur_bc()) {
  case Bytecodes::_invokeinterface:
  case Bytecodes::_invokevirtual:
  case Bytecodes::_invokespecial:
  case Bytecodes::_invokestatic:
  case Bytecodes::_invokedynamic:
    break;
  default:
    ShouldNotReachHere();
  }
#endif
  if (has_index_u4())
    return get_index_u4();  // invokedynamic
  return get_index_u2_cpcache();
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_method
//
// If this is a method invocation bytecode, get the invoked method.
// Additionally return the declared signature to get more concrete
// type information if required (Cf. invokedynamic and invokehandle).
ciMethod* ciBytecodeStream::get_method(bool& will_link, ciSignature* *declared_signature_result) {
  VM_ENTRY_MARK;
  ciEnv* env = CURRENT_ENV;
  constantPoolHandle cpool(_method->get_Method()->constants());
  ciMethod* m = env->get_method_by_index(cpool, get_method_index(), cur_bc(), _holder);
  will_link = m->is_loaded();

  // Use the MethodType stored in the CP cache to create a signature
  // with correct types (in respect to class loaders).
  if (has_method_type()) {
    ciSymbol*     sig_sym     = env->get_symbol(cpool->symbol_at(get_method_signature_index()));
    ciKlass*      pool_holder = env->get_klass(cpool->pool_holder());
    ciMethodType* method_type = get_method_type();
    ciSignature* declared_signature = new (env->arena()) ciSignature(pool_holder, sig_sym, method_type);
    (*declared_signature_result) = declared_signature;
  } else {
    (*declared_signature_result) = m->signature();
  }
  return m;
}

// ------------------------------------------------------------------
// ciBytecodeStream::has_appendix
//
// Returns true if there is an appendix argument stored in the
// constant pool cache at the current bci.
bool ciBytecodeStream::has_appendix() {
  VM_ENTRY_MARK;
  constantPoolHandle cpool(_method->get_Method()->constants());
  return ConstantPool::has_appendix_at_if_loaded(cpool, get_method_index());
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_appendix
//
// Return the appendix argument stored in the constant pool cache at
// the current bci.
ciObject* ciBytecodeStream::get_appendix() {
  VM_ENTRY_MARK;
  constantPoolHandle cpool(_method->get_Method()->constants());
  oop appendix_oop = ConstantPool::appendix_at_if_loaded(cpool, get_method_index());
  return CURRENT_ENV->get_object(appendix_oop);
}

// ------------------------------------------------------------------
// ciBytecodeStream::has_method_type
//
// Returns true if there is a MethodType argument stored in the
// constant pool cache at the current bci.
bool ciBytecodeStream::has_method_type() {
  GUARDED_VM_ENTRY(
    constantPoolHandle cpool(_method->get_Method()->constants());
    return ConstantPool::has_method_type_at_if_loaded(cpool, get_method_index());
  )
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_method_type
//
// Return the MethodType stored in the constant pool cache at
// the current bci.
ciMethodType* ciBytecodeStream::get_method_type() {
  GUARDED_VM_ENTRY(
    constantPoolHandle cpool(_method->get_Method()->constants());
    oop method_type_oop = ConstantPool::method_type_at_if_loaded(cpool, get_method_index());
    return CURRENT_ENV->get_object(method_type_oop)->as_method_type();
  )
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_declared_method_holder
//
// Get the declared holder of the currently referenced method.
//
// Usage note: the holder() of a ciMethod class returns the canonical
// holder of the method, rather than the holder declared in the
// bytecodes.
//
// There is no "will_link" result passed back.  The user is responsible
// for checking linkability when retrieving the associated method.
ciKlass* ciBytecodeStream::get_declared_method_holder() {
  VM_ENTRY_MARK;
  constantPoolHandle cpool(_method->get_Method()->constants());
  bool ignore;
  // report as MethodHandle for invokedynamic, which is syntactically classless
  if (cur_bc() == Bytecodes::_invokedynamic)
    return CURRENT_ENV->get_klass_by_name(_holder, ciSymbol::java_lang_invoke_MethodHandle(), false);
  return CURRENT_ENV->get_klass_by_index(cpool, get_method_holder_index(), ignore, _holder);
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_method_holder_index
//
// Get the constant pool index of the declared holder of the method
// referenced by the current bytecode.  Used for generating
// deoptimization information.
int ciBytecodeStream::get_method_holder_index() {
  ConstantPool* cpool = _method->get_Method()->constants();
  return cpool->klass_ref_index_at(get_method_index());
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_method_signature_index
//
// Get the constant pool index of the signature of the method
// referenced by the current bytecode.  Used for generating
// deoptimization information.
int ciBytecodeStream::get_method_signature_index() {
  GUARDED_VM_ENTRY(
    ConstantPool* cpool = _holder->get_instanceKlass()->constants();
    const int method_index = get_method_index();
    const int name_and_type_index = cpool->name_and_type_ref_index_at(method_index);
    return cpool->signature_ref_index_at(name_and_type_index);
  )
}

// ------------------------------------------------------------------
// ciBytecodeStream::get_resolved_references
ciObjArray* ciBytecodeStream::get_resolved_references() {
    VM_ENTRY_MARK;
    // Get the constant pool.
  ConstantPool*        cpool   = _holder->get_instanceKlass()->constants();

  // Create a resolved references array and return it.
  return CURRENT_ENV->get_object(cpool->resolved_references())->as_obj_array();
  }

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